Reconstructing a light pseudoscalar in the Type-X two Higgs doublet model

Abstract

We investigate the detectability as well as reconstructibility of a light pseudoscalar particle A, of mass in the 50–60 GeV range, which is still allowed in a Type-X (lepton-specific) two-Higgs doublet scenario. Such a pseudoscalar can be pair-produced in the decay of the 125 GeV scalar h. The light pseudoscalar in the aforementioned range, helpful in explaining the muon anomalous magnetic moment, has not only substantial branching ratio in the channel but also one of about in the final state. We show how to faithfully reconstruct the A mass using the mode, and establish the existence of a pseudoscalar around 50–60 GeV, using the process . This is the most reliable way of reconstructing the light A mass, with a statistical significance that amounts to discovery, with a few hundred (or less) of integrated luminosity.